Objective:To explore the effect of cathepsin L (CTSL) inhibitor on apoptosis of retinal pigment epithelial (RPE) cells and mitochondrial oxidative stress.Methods:RPE cells were cultured in vitro and divided into control group, hydrogen peroxide (H 2O 2) group, and H 2O 2+CTSL inhibitor group. The cells of H 2O 2 group and H 2O 2+CTSL inhibitor group were incubated in the medium containing 400 μmol/L H 2O 2 for 24 hours and 10 μmol/L CTSL inhibitor was added in H 2O 2+CTSL inhibitor group at the same time. The cells of normal group were routinely cultured cells. The follow-up experiment was carried out 24 hours after modeling. The rate of apoptosis was detected by flow cytometry. The expression of CTSL was detected by immunofluorescence staining, Western blot and real time-polymerase chain reaction. The level of mitochondrial super oxide was detected by MitoSOX fluorescent probe, and the mitochondrial structure was observed after MitoTracker staining, the average area, form factors, and branch of mitochondria were quantitatively analyzed. The two groups were compared using two-tailed Student t test, while numerous groups were compared using one-way ANOVA. Results:Compared with control group, the rate of apoptosis in H 2O 2 group was significantly higher ( t=3.307, P=0.029 7), the expression level of CTSL was significantly increased ( t=19.950, 6.916, 14.220; P<0.05). Compared with H 2O 2 group, the expression level of CTSL, the rate of apoptosis and the mitochondrial ROS level in H 2O 2+CTSL inhibitor group were significantly lower ( t=11.940, 4.718, 16.680; P<0.05). The mitochondria of H 2O 2+CTSL inhibitor group were elongated, oval-shaped or rod-shaped, while the mitochondria of H 2O 2 group lost their continuous contour shape and complete structure. The differences of the average area, form factors, and brach of mitochondria among 4 groups were statistically significant ( F=251.700, 34.010, 60.500; P<0.000 1). Conclusions:H 2O 2 can significantly induce apoptosis in RPE cells and increase CTSL expression. CTSL inhibitor can inhibit the H 2O 2-induced apoptosis of RPE cells, lower the mitochondrial super oxide level, and successfully repair the mitochondrial structure.

Radiotherapy (RT) can potentially induce systemic immune responses by initiating immunogenic cell death (ICD) of tumor cells. However, RT-induced antitumor immunologic responses are sporadic and insufficient against cancer metastases. Herein, we construct multifunctional self-sufficient nanoparticles (MARS) with dual-enzyme activity (GOx and peroxidase-like) to trigger radical storms and activate the cascade-amplified systemic immune responses to suppress both local tumors and metastatic relapse. In addition to limiting the Warburg effect to actualize starvation therapy, MARS catalyzes glucose to produce hydrogen peroxide (H₂O₂), which is then used in the Cu⁺-mediated Fenton-like reaction and RT sensitization. RT and chemodynamic therapy produce reactive oxygen species in the form of radical storms, which have a robust ICD impact on mobilizing the immune system. Thus, when MARS is combined with RT, potent systemic antitumor immunity can be generated by activating antigen-presenting cells, promoting dendritic cells maturation, increasing the infiltration of cytotoxic T lymphocytes, and reprogramming the immunosuppressive tumor microenvironment. Furthermore, the synergistic therapy of RT and MARS effectively suppresses local tumor growth, increases mouse longevity, and results in a 90% reduction in lung metastasis and postoperative recurrence. Overall, we provide a viable approach to treating cancer by inducing radical storms and activating cascade-amplified systemic immunity.

Neoadjuvant chemotherapy has become an indispensable weapon against high-risk resectable cancers, which benefits from tumor downstaging. However, the utility of chemotherapeutics alone as a neoadjuvant agent is incapable of generating durable therapeutic benefits to prevent postsurgical tumor metastasis and recurrence. Herein, a tactical nanomissile (TALE), equipped with a guidance system (PD-L1 monoclonal antibody), ammunition (mitoxantrone, Mit), and projectile bodies (tertiary amines modified azobenzene derivatives), is designed as a neoadjuvant chemo-immunotherapy setting, which aims at targeting tumor cells, and fast-releasing Mit owing to the intracellular azoreductase, thereby inducing immunogenic tumor cells death, and forming an in situ tumor vaccine containing damage-associated molecular patterns and multiple tumor antigen epitopes to mobilize the immune system. The formed in situ tumor vaccine can recruit and activate antigen-presenting cells, and ultimately increase the infiltration of CD8⁺ T cells while reversing the immunosuppression microenvironment. Moreover, this approach provokes a robust systemic immune response and immunological memory, as evidenced by preventing 83.3% of mice from postsurgical metastasis or recurrence in the B16-F10 tumor mouse model. Collectively, our results highlight the potential of TALE as a neoadjuvant chemo-immunotherapy paradigm that can not only debulk tumors but generate a long-term immunosurveillance to maximize the durable benefits of neoadjuvant chemotherapy.